
\section{Implementation \& Validation: Working Scenario}
\label{sec:validation}
To pass an online certification exam, a user has to provide his name and his email address to access the certification web site which provides several exam categories with different difficulty level. 
Before accessing a given exam, the user has to register to the exam, his registration remains available during 20 minutes and it is validated after the signature of a license agreemnt and after 
the validation of the payment. Each exam lasts 3 hours and it is composed of three modules. To validate the exam, the user needs to validate each module. 
The maximum time limit to treat each module is one hour.
After the validation of the whole exam, the system displays the user's score and mentions if he has passed or failed his exam. 
The user is then asked to fill a customer satisfaction form before logging out.
All operations are achieved in the system.

\subsection{Pre-obligations}
\begin{itemize}
 \item The user needs to provide a name and an email address
 \item The user has to register
 \item The user has to validate a license agreement
 \item The user needs to pay (20 mn maximum after registration)
\end{itemize}

\subsection{On-obligations}

\begin{itemize}
 \item The user has to validate each module (every hour)
 \item The user has to fill a customer satisfaction form 
\end{itemize}

\subsection{Post-obligations}